A recent innovation in the field of flash photography has been the packaged linear flashlamp array. Developed for use with a highly automated camera, this flashlamp packaging arrangement is formed of two operational faces, each exhibiting an array of five flashlamps. When utilized in conjunction with a camera, a rapid succession of photographic cycles may be carried out without resort to mechanically indexing or aligning flashlamps following each exposure. As a consequence, cameras utilizing the array may be designed having a more convenient and compact size. Described in detail in U.S. Pat. Nos. 3,598,984 and 3,598,985, the dual arrays of flashlamps are compactly packaged by internesting the oppositely disposed flashlamps of each face thereof. The igniting terminals of individual lamps within the packaged arrays are connected by printed circuit technique to a downwardly extending blade mount, each side of which is configured to expose five input contacts and a common bus or lead. By inserting the downwardly extending blade mount within an appropriate mount or receptacle, electrical connection is made with the five input contacts of an outwardly or operationally facing array of the flashlamp and the noted common lead.
To ignite successive ones of those flashlamps within an appropriately oriented operational face of an array, flash firing circuits are incorporated. Typical designs for such circuits are those described in U.S. Pat. No. 3,676,045 and in application for U.S. Pat. by S. Ellin, Ser. No. 353,007, entitled "Flashlamp Signaling Circuit Employing Logic Signal Activation", filed Apr. 20, 1973, which, in turn, is a continuation-in-part of application Ser. No. 321,993, filed Jan. 8, 1973. For practical applications, these circuits are integrated structures capable of being triggered by low level logic or by pulse triggering. Inasmuch as the circuits are structured as "chip" modules, the period of their enablement or energization necessarily must be limited to prevent burn-out failures and the like.
In many photographic applications, for instance, portraiture, it is desirable to illuminate a subject from two directional aspects. For instance, a lighting source slaved to a camera mounted transient illumination source may be used to ameliorate background shadows or to provide highlighting effects and the like. Generally, such a slave unit requires cable connection to the flash synchronization firing system of the camera or incorporates a light responsive logic circuit to fire an auxiliary flashlamp in response to a witnessing of the light output of a camera mounted flash unit. In view of the convenience of the above-described linear array flash units, it is desirable that a slave unit be capable of accommodating such arrays by incorporating the above-described flash firing circuits. However, because of the unique structure of the units and the specialized demands imposed by their firing structures, such adaptation of remote slave units is not readily available. For instance, enablement of the firing circuits must be limited to a very short interval, for example, about 40 ms, to avoid chip burn-out. Further, should the device inadvertently be exposed to relatively high level steady-state illumination, as may be encountered at a sunny window, a firing circuit may react to rapidly and sequentially fire all lamps within a noted operational face. This effect is known as "cascading".